The invention relates to a control valve which is back-and-forth movable in its longitudinal direction, the control valve being arranged to open and close pressure channels leading to a percussion device. The invention further relates to a method of controlling a working cycle of a percussion device, and to a percussion device for breaking rock.
In rock breaking, percussion hammers and rock drills are used that are equipped with a percussion device for issuing impact pulses to the rock through a tool. A percussion device comprises an impact element, such as a percussion piston, whose working pressure surfaces may be affected by a pressure medium and which impact element is arranged to produce the necessary impact pulses. The pressure medium affecting the impact element may be controlled by a control valve connected to open and close pressure medium channels. As is well known in the art, an increase in the impact frequency of a percussion device usually enhances the breaking of rock. However, the existing control valves restrict the increasing of the impact frequency.